The present disclosure relates to fuel cell systems. In particular, the present disclosure relates to a fuel cell module housing that includes a plurality of fuel cell stacks that can be individually erected, installed, repaired or replaced in the field.
A fuel cell is a device which uses an electrochemical reaction to convert chemical energy stored in a fuel such as hydrogen or methane into electrical energy. In general, fuel cells include an anode to catalytically react with the fuel and a cathode in fluid communication with an oxidant such as air.
Fuel cells are typically arranged in a stacked relationship. A fuel cell stack includes many individual cells positioned between a fixed end plate and a free end plate. One fuel cell stack configuration includes an externally manifolded stack, wherein the fuel cell stack is left open on its sides and a fluid such as a fuel or oxidant is delivered by way of manifolds sealed to peripheral portions of respective sides of the fuel cell stack. The manifolds thus provide sealed passages for delivering the fuel and the oxidant gases to the fuel cells and directing the flow of such gases in the stack, thereby preventing those gases from leaking either to the environment or to the other manifolds. Such manifolds are typically used in Molten Carbonate Fuel Cells (MCFC) which operate at approximately 650° C. During operation of MCFCs, the fuel cells and endplates can move relative to the fuel cell manifolds.
Conventional fuel cells typically include an anode and a cathode separated by an electrolyte contained in an electrolyte matrix. The anode, the cathode, the electrolyte and the electrolyte matrix are disposed between a first collector and a second collector, with the first collector adjacent to the anode and the second collector adjacent to the cathode. Fuel flows to the anode via the first collector and an oxidant flows to the cathode via the second collector. The fuel cell oxidizes the fuel in an electrochemical reaction which releases a flow of electrons between the anode and cathode, thereby converting chemical energy into electrical energy.
The fuel cells described above can be stacked in series with separator plates disposed between adjacent fuel cells and end plates (e.g., a fixed end plate and a free end plate) disposed on opposing ends of the fuel cell stack. Alternatively, the fuel cells described above can be stacked in parallel, and connected, for example, by a power bus. Fuel cells are stacked to increase the electrical energy they produce. Fuel cell stacks have a negative side with a negative end cell and a positive side with a positive end cell.
In order to increase power output without having to unduly increase the size (i.e., surface area) of individual fuel cells or the number of individual fuel cells in a fuel cell stack, a plurality of fuel cell stacks are electrically and fluidly connected. As described, for example, in U.S. Patent Application Publication No. 2011/0269052, in systems including a plurality of fuel cell stacks, an “open-cell design” in which fuel cell stacks are placed into a relatively large enclosure that directs fuel and air into stacks housed within the enclosure and receives tail gas and spent air from those stacks for optional further processing and ultimate discharge to the outside. Alternatively, an “enclosed-cell design” may be used in which internal manifold channels are used for fuel and air flow.
For large module enclosures including a large number of fuel cell stacks, it is difficult or impossible to transport the module due to size and cost consideration. A power plant may include several of these large module enclosures. During repair or replacement of an individual fuel cell stack in the large module enclosure, all of the fuel cell stacks need to be taken offline (i.e., shut down) because when the “hot zone” containing the fuel cell stacks is opened, the zone would be cooled down. As a result, the remaining fuel cell stacks would likely not be able to operate at the lower temperatures.
A need exists for improved technology, including technology related to a power plant including a plurality of fuel cell module housings (i.e., module enclosures) sized such that only a partial shutdown is required when one of the plurality of fuel cell module housings is opened up to repair or replace an individual fuel cell stack. A need also exists for improved technology relating to a fuel cell module housing in which individual hot fuel cell stacks may be removed, and repaired or replaced from the housing, without having to cool down the remaining plurality of fuel cell stacks in the housing.